Nikko Bay

We've done a lot of our scientific work in Nikko Bay, one of the protected nearshore environments in Palau's Rock Islands that have received some attention in the news lately due to a recent paper out of Woods Hole Oceanographic Institution. They found that although these bays have relatively acidic waters, they have greater coral cover and diversity than the less acidic outer reefs. This is an exciting finding because in general, lower pH disrupts corals' ability to form their calcified skeletons, so we associate ocean acidification with sparser, more fragile, less diverse corals.

Average ocean pH is around 8.3, and in our field trips to Nikko Bay, we measured water pH of around 7.9-8.1 (These are still basic values; "ocean acidification" is a rather misleading term). It's thought that these bays have lower pH because they are surrounded by heavily vegetated islands, and trees and foliage constantly fall into the water, releasing acids as they decompose. The bays are slow to exchange their water with the ocean, so the acids can accumulate to a level generally harmful to corals. Nikko Bay's corals have evolved to thrive under these acidified conditions over thousands of years, so while these "acidification-resistant" corals may represent hope for threatened reefs worldwide, it may be that the time frame of current ocean change may be too rapid for most corals to adapt. 

Nikko Bay. Photo by Susy Gritsch. 

Photo by Susy Gritsch. 

Near the surface, Nikko Bay has sunlit corals and tons of small fish, but a few meters down everything is murky and silent. It brings to mind a long-forgotten storage closet of an extravagant carnival: gaudy colors and shapes left tumbled and dusty with sediment, strands of mucus hanging off coral edges like cobwebs. I emerged from my first few dives with "Once Upon a December" stuck in my head.